Persinal Identification Number (PIN): Definition and Explanation

What is a PIN and How do you Use It?

Entering PIN
Cover your hand as you enter your PIN. Image Source/Getty Images

A personal identification number (PIN) is a security code for verifying your identity. Similar to a password, your PIN should be kept secret because it allows access to important services (like the ability to withdraw cash, view or change personal information, and more). Unlike a typical password on your bank account, a PIN is numeric only – there are no letters or other characters in a PIN.

PINs are most commonly used for financial transactions and (historically) student loans, but they can be used for anything from unlocking a door to unlocking a phone.

PINs are sometimes called “pin numbers,” which is redundant because the word "number" is already included in “PIN.”

Financial PINs

When you take money out of an ATM using a debit or credit card, you need to enter a PIN to prove that you're authorized to make the withdrawal. The PIN serves as a secondary form of verification (anybody could have possession of the card, but only you should know the PIN that works with the card). In many cases, your PIN is a four-digit number, such as 1234 (obviously you’d want to use a PIN that is harder to guess).

You might also need to use a PIN to use your debit or credit card at a retailer. Again, the PIN proves that you are authorized to use the card. In the United States, chip-enabled cards sometimes require a PIN at checkout, but a signature is more common. In other countries, entering a PIN is the norm – and some cards issued in the US are not compatible with those payment systems (so check with your bank before you take your card out of the country).

Aside from PINs you set up with your bank our credit union, almost any organization you work with might ask you to establish a PIN. The concept is similar: this is a secret code that verifies your identity. For example, you might need a PIN to:

  • Access your 401k account for the first time.
  • Make changes to your mobile phone account (address or service plan)
  • File and pay taxes electronically.

Student Loans

In the past, PINs were an important part of your application for federal student loans. After 2015, PINs were replaced with FSA IDs, which are more secure.

PIN Security

Because PINs protect sensitive information (and your cash), you’ll want to use a PIN that is difficult to guess. Avoid including the following items in your PIN:

  • Simple number sequences like 1234 or 0000 (including repetition: 1122 or 2233)
  • Significant dates such as your birth year or spouse’s birthday
  • Any part of your Social Security Number
  • Any part of your address or phone number

Longer PINs are safer than shorter PINs because there are more ways to mix the numbers together. For example, if you use a four digit PIN, you can come up with 10,000 variations (starting with 0000, 0001, 0002, and so on). With a six-digit PIN, there are one million potential codes, so it’s much more difficult for thieves and computer programs to successfully guess your PIN.

Anytime you have the option, go with a longer PIN.

Most security systems lock your account (at least temporarily) after three unsuccessful attempts. This gives you and your bank a chance to figure out what’s going on, and it keeps progress painfully slow for anybody trying to guess your PIN.

Keep it Secret, but Accessible

Because the PIN authorizes you (or whoever knows it) to access sensitive information, it's essential to keep the number secret. Protect it, and never write it on your ATM or debit card – thieves know to look for 4 digit codes written on the back of stolen cards.

When you enter your PIN at an ATM or cash register, cover the keypad with your free hand so that nobody can see what you type in. Hidden cameras are sometimes installed at ATMs and other devices for recording PINs. If you want to be extra safe, touch some of the other keys (which aren’t part of your PIN), which can help thwart heat-sensitive cameras and other tactics.

PINs can be hard to remember – especially if you’ve got a stack of debit cards. This creates a challenging situation: good security is more difficult to stick with.

As a result, you may be tempted to take shortcuts (like re-using the same PIN or using numbers from your birthday). Fortunately, there are several tricks that make it easy to store PINs safely (while making them easy to access or remember). For a list of ideas, see Secrets of Great PIN Numbers.

What is your PIN?

If you don’t know your PIN, you might still need to get it from your financial institution. In many cases, you do not get to choose your initial PIN – it will be mailed to you separately (in case your card is stolen from the mail). You’ll generally have the option to change your PIN, and you might be required to do so.

However, some banks allow you to choose your PIN yourself as your card is printed.

When you lose or forget your PIN, you’ll need to reset it. This is generally done by mail or with a visit to a bank branch (assuming the PIN is for your bank account).